High blood sugar (hyperglycemia) occurs when there’s too much glucose circulating in your bloodstream. If left unchecked, it can lead to serious complications, especially for people with diabetes or prediabetes. Recognizing the early warning signs can prompt you to take action quickly and prevent emergencies like diabetic ketoacidosis or long-term organ damage.
Here are the most common and important high blood sugar warning signs, ranked roughly by how frequently they appear:
1. Frequent Urination (Polyuria)
Your kidneys work overtime to flush out excess sugar through urine. This causes you to urinate more often, especially at night.
2. Excessive Thirst (Polydipsia)
As you lose more fluid through frequent urination, your body triggers intense thirst to replace it. You may feel like you can’t drink enough water.
3. Extreme Hunger (Polyphagia)
Even after eating, cells aren’t getting the glucose they need because insulin isn’t working properly. Your body sends hunger signals trying to get more energy.
4. Unexplained Fatigue or Weakness
When cells can’t absorb glucose effectively, they become starved for energy. This leaves you feeling constantly tired, sluggish, or weak.
5. Blurred Vision
High blood sugar pulls fluid from the lenses of your eyes, affecting your ability to focus and causing temporary blurred vision.
6. Slow-Healing Cuts and Frequent Infections
Elevated glucose levels impair white blood cell function and circulation, making it harder for wounds to heal and increasing risk of skin, gum, yeast, or urinary tract infections.
7. Dry Mouth and Itchy Skin
Dehydration from frequent urination often leads to a persistently dry mouth and dry, itchy skin—especially on the legs and feet.
8. Tingling or Numbness in Hands and Feet (Neuropathy)
Over time, high blood sugar damages nerves, causing tingling, burning, or numbness, usually starting in the extremities.
9. Unexpected Weight Loss
In type 1 diabetes especially, the body starts burning fat and muscle for energy when it can’t use glucose, leading to rapid, unexplained weight loss.
10. Headaches
Dehydration and fluctuating glucose levels can trigger frequent headaches or migraines.
11. Fruity Breath or Nausea (Emergency Signs)
A sweet or fruity odor on the breath, along with nausea, vomiting, or rapid breathing, can indicate diabetic ketoacidosis (DKA)—a life-threatening condition requiring immediate medical attention.
When to Check Your Blood Sugar
If you experience two or more of these symptoms—especially frequent urination, excessive thirst, and fatigue—test your blood sugar right away. The American Diabetes Association suggests seeking urgent care if your reading is:

≥240 mg/dL (13.3 mmol/L) with ketones in urine, or
≥300 mg/dL (16.7 mmol/L) even without ketones.

Who Is at Risk?
Anyone can experience temporary high blood sugar, but you’re at higher risk if you have:

Type 1 or type 2 diabetes
Prediabetes or insulin resistance
A family history of diabetes
Obesity
Are taking certain medications (e.g., steroids)

Quick Tips to Lower High Blood Sugar

Drink plenty of water
Exercise lightly (if safe and no ketones present)
Take prescribed insulin or medication
Eat low-carb, high-fiber foods
Contact your doctor if levels stay above 240 mg/dL for several hours

Final Note
High blood sugar symptoms often develop gradually, so many people ignore them until they become severe. Early detection and management can prevent serious complications like heart disease, kidney damage, vision loss, and nerve damage.
If you’re experiencing several of these warning signs, check your blood sugar immediately and contact your healthcare provider. Never ignore persistent symptoms—your health is worth it.
This article is for informational purposes only and is not a substitute for professional medical advice. Always consult your doctor for diagnosis and treatment.
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Stay aware, stay healthy!